Noda did not specify what health problem Putin might have, but Kremlin observers for months have speculated that the Russian president, an avid sportsman, was suffering from a serious back injury.

The chatter began in September when guests and journalists at the Asia-Pacific Economic Cooperation summit in Russia's far eastern city of Vladivostok saw Putin limping. A spokesman said then that Putin had strained a muscle during a workout.

The spokesman, Dmitry Peskov, on Friday told the Interfax news agency that there had been no fixed dates for Noda's visit and that he may come to Russia in January.

Peskov said this week that rumors about Putin's back problems "were strongly exaggerated." Putin was continuing to work as always, he said.

"He doesn't intend to drop his sports workouts and that is why, like with any athlete, he can have some small pain, be it in the back, in the leg or in the arm," Peskov said in an interview with the daily Komsomolskaya Pravda. "But that never affected his working ability."

Belarusian President Alexander Lukashenko said in a Reuters interview this week that Putin's back was the reason he did not participate in a friendly hockey match between officials of the two countries.

"He adores judo," Lukashenko said of Putin, who has earned a black belt. "He raised an opponent and threw him and harmed his spine."

The Kremlin reacted to Lukashenko's statement by announcing Putin's travel schedule, which includes a trip to Turkey on Monday.

Putin, known for promoting an image as a tough and brave leader, in September flew a motorized hang glider with the intention of teaching endangered Siberian cranes a new migration path.

In recent months, Putin, who turned 60 in October, has canceled a number of foreign visits and cut back on trips to the Kremlin from his residence near Moscow.

Peskov has said Putin cut his trips to the Kremlin because he didn't want to further complicate bad Moscow traffic.

Whatever is or isn't happening with Putin, his concern with his image and physical appearance remains intact, Stanislav Belkovsky, president of the Moscow-based think tank National Strategy Institute, said in an interview.

"Of course the Kremlin and its press service will be denying everything until they can no longer deny that the president is sick," Belkovsky said. "We will find out about it on Dec. 3, the date for his planned visit to Istanbul."